Semiconductor device and method of manufacturing the same

ABSTRACT

A semiconductor device including: a semiconductor substrate including an electrode; a resin protrusion formed on the semiconductor substrate; and an interconnect electrically connected to the electrode and formed to extend over the resin protrusion. The interconnect includes a first portion formed on a top surface of the resin protrusion and a second portion formed on a side of a lower portion of the resin protrusion. The second portion has a width smaller than a width of the first portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. Ser. No. 12/685,169 filed onJan. 11, 2010, which is a divisional application of U.S. Ser. No.11/444,271 filed on May 31, 2006 (now U.S. Pat. No. 7,671,476), whichclaims priority to Japanese Patent Application No. 2005-190448, filed onJun. 29, 2005, all of which are hereby incorporated by reference intheir entireties.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device and a method ofmanufacturing the same.

In order to reduce the size of electronic parts, it is preferable thatthe external shape of the semiconductor device be small. Along withdiversification of the functions of semiconductor devices, the degree ofintegration of an integrated circuit formed on a semiconductor chip hasbeen increased. Therefore, the number of pins of the semiconductor chiphas been increased. Specifically, a semiconductor device has beendeveloped which allows a reduction in size of the semiconductor deviceand an increase in the degree of integration of the integrated circuit.

As a semiconductor device which can satisfy such demands, asemiconductor device in which an interconnect is formed on asemiconductor chip has attracted attention (see JP-A-2-272737). In thistype of semiconductor device, since the external shape of thesemiconductor device can be made approximately equal to the externalshape of the semiconductor chip, the size of the semiconductor devicecan be reduced.

The above semiconductor device is required to exhibit high reliability.In addition, a method of efficiently manufacturing the abovesemiconductor device while ensuring reliability has been demanded.

SUMMARY

According to a first aspect of the invention, there is provided asemiconductor device comprising:

a semiconductor substrate including an electrode;

a resin protrusion formed on the semiconductor substrate; and

an interconnect electrically connected to the electrode and formed toextend over the resin protrusion, the interconnect including a firstportion formed on a top surface of the resin protrusion and a secondportion formed on a side of a lower portion of the resin protrusion, andthe second portion having a width smaller than a width of the firstportion.

According to a second aspect of the invention, there is provided amethod of manufacturing a semiconductor device comprising:

providing a semiconductor substrate having an electrode;

forming a resin protrusion on the semiconductor substrate;

forming an interconnect which is electrically connected to the electrodeand includes a first portion formed on a top surface of the resinprotrusion and a second portion formed on a lower portion of the resinprotrusion and having a width smaller than a width of the first portion;and

removing at least part of a portion of the lower portion of the resinprotrusion which contacts the second portion.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIGS. 1A and 1B are views illustrative of a semiconductor deviceaccording to one embodiment of the invention.

FIG. 2 is a view illustrative of a semiconductor device according to oneembodiment of the invention.

FIG. 3 is a view showing an electronic module on which a semiconductordevice according to one embodiment of the invention is mounted.

FIGS. 4A and 4B are views illustrative of a method of manufacturing asemiconductor device according to one embodiment of the invention.

FIGS. 5A to 5C are views illustrative of a method of manufacturing asemiconductor device according to one embodiment of the invention.

FIG. 6 is a view illustrative of a method of manufacturing asemiconductor device according to one embodiment of the invention.

FIG. 7 is a view illustrative of a method of manufacturing asemiconductor device according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENT

The invention may provide a highly reliable semiconductor device and amethod of manufacturing the same.

(1) According to one embodiment of the invention, there is provided asemiconductor device comprising:

a semiconductor substrate including an electrode;

a resin protrusion formed on the semiconductor substrate; and

an interconnect electrically connected to the electrode and formed toextend over the resin protrusion, the interconnect including a firstportion formed on a top surface of the resin protrusion and a secondportion formed on a side of a lower portion of the resin protrusion, andthe second portion having a width smaller than a width of the firstportion.

In this embodiment, a highly reliable semiconductor device can beprovided in which an electrical short circuit due to migration rarelyoccurs between two adjacent interconnects.

(2) In this semiconductor device,

the interconnect may include an extension portion extending from thesecond portion, and a conductive portion connecting the extensionportion and the electrode; and

the extension portion may have a width smaller than a width of theconductive portion.

(3) In this semiconductor device, the extension portion may have a widthequal to the width of the second portion.

(4) In this semiconductor device, a portion of the interconnect formedon the semiconductor substrate may have a width equal to the width ofthe second portion.

(5) In this semiconductor device, the second portion of the interconnectmay not be secured to the resin protrusion.

This allows a semiconductor device exhibiting high reliability againststress can be provided.

(6) According to one embodiment of the invention, there is provided amethod of manufacturing a semiconductor device comprising:

providing a semiconductor substrate having an electrode;

forming a resin protrusion on the semiconductor substrate;

forming an interconnect which is electrically connected to the electrodeand includes a first portion formed on a top surface of the resinprotrusion and a second portion formed on a lower portion of the resinprotrusion and having a width smaller than a width of the first portion;and

removing at least part of a portion of the lower portion of the resinprotrusion which contacts the second portion.

In this embodiment, a highly reliable semiconductor device can beprovided in which an electrical short circuit due to migration rarelyoccurs between two adjacent interconnects and which exhibits highreliability against stress.

The embodiments of the invention will be described below, with referenceto the drawings. Note that the invention is not limited to the followingembodiments.

Semiconductor Device

FIGS. 1 to 3 are views illustrative of a semiconductor device accordingto one embodiment of the invention. FIG. 1A is a top view of asemiconductor device 1 according to one embodiment of the invention, andFIG. 1B is a partially enlarged view of the cross section along the lineIB-IB shown in FIG. 1A. FIG. 2 is a schematic view of the semiconductordevice 1, and FIG. 3 is a view showing an electronic module on which thesemiconductor device 1 is mounted.

As shown in FIGS. 1A to 2, the semiconductor device according to thisembodiment includes a semiconductor substrate 10. The semiconductorsubstrate 10 may be a silicon substrate, for example. The semiconductorsubstrate 10 may be in the shape of a chip (see FIG. 3). The surface(active surface) of the semiconductor substrate 10 on which an electrode14 is formed may be rectangular. The active surface of the semiconductorsubstrate 10 may be square (not shown). Or, the semiconductor substrate10 may be in the shape of a wafer (see FIG. 4A). One or more integratedcircuits 12 may be formed on the semiconductor substrate 10 (oneintegrated circuit 12 may be formed on a semiconductor chip and two ormore integrated circuits 12 may be formed on a semiconductor wafer) (seeFIG. 1B). The configuration of the integrated circuit 12 is notparticularly limited. For example, the integrated circuit 12 may includean active element such as a transistor and a passive element such as aresistor, coil, or capacitor.

As shown in FIGS. 1A and 1B, the semiconductor substrate 10 includes theelectrode 14. The electrode 14 may be electrically connected with theinside of the semiconductor substrate 10. The electrode 14 may beelectrically connected with the integrated circuit 12. The electrode 14may also include a conductor which is not electrically connected withthe integrated circuit 12. The electrode 14 may be part of an internalinterconnect of the semiconductor substrate. The electrode 14 may be aportion of the internal interconnect of the semiconductor substrate usedfor electrical connection with the outside. The electrode 14 may beformed of a metal such as aluminum or copper.

As shown in FIG. 1B, the semiconductor substrate 10 may include apassivation film 16. The passivation film 16 may be formed to expose theelectrode 14. The passivation film 16 may have an opening which exposesthe electrode 14. The passivation film 16 may be formed to partiallycover the electrode 14. The passivation film 16 may be formed to coverthe periphery of the electrode 14. The passivation film may be aninorganic insulating film formed of SiO₂, SiN, or the like. Thepassivation film 16 may be an organic insulating film formed of apolyimide resin or the like.

As shown in FIGS. 1A to 2, the semiconductor device according to thisembodiment includes a resin protrusion 20 formed on the semiconductorsubstrate 10. The resin protrusion 20 may be formed on the passivationfilm 16. The material for the resin protrusion 20 is not particularlylimited. A known material may be used. For example, the resin protrusion20 may be formed using a resin such as a polyimide resin,silicone-modified polyimide resin, epoxy resin, silicone-modified epoxyresin, benzocyclobutene (BCB), or polybenzoxazole (PBO). The shape ofthe resin protrusion 20 is not particularly limited. For example, theresin protrusion 20 may be formed linearly (see FIGS. 1A and 2). Whenthe semiconductor substrate 10 is rectangular, the resin protrusion 20may be formed to extend along the long side of the semiconductorsubstrate 10. The surface of the resin protrusion 20 may be curved. Inthis case, the cross-sectional shape of the resin protrusion 20 may be asemicircle (see FIG. 1B). The resin protrusion 20 may have ahemispherical shape (not shown).

As shown in FIGS. 1A to 2, the semiconductor device according to thisembodiment includes an interconnect 30. The interconnect 30 iselectrically connected with the electrode 14. The interconnect 30 isformed to extend over the resin protrusion 20. The interconnect 30includes a first portion 31 formed on the top surface of the resinprotrusion 20, and a second portion 32 formed on the side of the lowerportion of the resin protrusion 20. As shown in FIGS. 1A and 2, thesecond portion 32 has a width smaller than that of the first portion 31.The first portion 31 may be secured to the resin protrusion 20. On theother hand, the second portion 32 may not be secured to the surface ofthe lower portion of the resin protrusion 20. As shown in FIG. 1B, thesecond portion 32 may be formed at an interval from the resin protrusion20. Note that the second portion 32 may be secured to the resinprotrusion 20 (see FIG. 7). The second portion 32 may be provided oneach side of the resin protrusion 20.

As shown in FIG. 1A, the interconnect 30 may include an extensionportion 34 extending to the second portion 32, and a conductive portion36 which connects the extension portion 34 and the electrode 14. Theextension portion 34 and the conductive portion 36 may be portionsprovided on the semiconductor substrate 10 (passivation film 16). Thefirst and second portions 31 and 32 may be electrically connected withthe electrode 14 through the conductive portion 36 and the extensionportion 34. The extension portion 34 may have a width smaller than thatof the conductive portion 36. The extension portion 34 may have a widthequal to that of the second portion 32. An end portion 35 of theinterconnect 30 may have a width greater than that of the second portion32. This allows the contact area between the interconnect 30 and thesemiconductor substrate 10 (passivation film 16) to be increased.Therefore, a highly reliable semiconductor device can be provided inwhich separation of the interconnect 30 rarely occurs.

Note that the interconnect 30 is not limited thereto. The portion of theinterconnect 30 formed on the semiconductor substrate 10 may have aconstant width (not shown). The portion of the interconnect 30 formed onthe semiconductor substrate 10 may have a width equal to that of thesecond portion 32.

The structure and the material of the interconnect 30 are notparticularly limited. For example, the interconnect 30 may be formed bya plurality of layers. In this case, the interconnect 30 may include afirst layer formed of titanium tungsten and a second layer formed ofgold (not shown). Or, the interconnect 30 may be formed by a singlelayer.

The semiconductor device 1 according to this embodiment may have theabove-described configuration. As described above, the interconnect 30includes the first portion 31 formed on the top surface of the resinprotrusion 20, and the second portion 32 disposed on the side of thelower portion of the resin protrusion 20. The second portion 32 has awidth smaller than that of the first portion 31. Therefore, thesemiconductor device 1 allows the interval between the second portions32 of two adjacent interconnects 30 to be increased. This prevents anelectrical short circuit due to migration from occurring between thesecond portions 32 of the interconnects 30. This effect is describedbelow in detail.

In the manufacture of the semiconductor device, a carbide layer may beformed on the surface of the resin protrusion 20. Since the carbidelayer has an insulation resistance lower than that of the resin, anelectrical short circuit tends to occur between two interconnects formedon the carbide layer in comparison with two interconnects formed on theresin layer. If the interconnects are scaled down and reduced in pitch,a decrease in the insulation resistance may affect the reliability ofthe semiconductor device.

A technology has been known in which the insulation resistance betweeninterconnects is secured by removing a carbide layer between twoadjacent interconnects in order to manufacture a highly reliablesemiconductor device. For example, a resin layer between two adjacentinterconnects is removed by O₂ plasma etching. However, the lowerportion of the resin protrusion 20 has an angle of about 90° withrespect to the semiconductor substrate 10. Therefore, it is difficult toefficiently and reliably remove the carbide layer formed on the surfaceof the lower portion of the resin protrusion 20 by a known method.

On the other hand, according to this embodiment, the second portion 32of the interconnect 30 formed on the side of the lower portion of theresin protrusion 20 has a width smaller than that of the first portion31. Therefore, the semiconductor device 1 allows the interval betweenthe second portions 32 of two adjacent interconnects 30 to be increased.This prevents an electrical short circuit from occurring between twoadjacent interconnects 30 even if the carbide layer is formed on thesurface of the lower portion of the resin protrusion 20 (even if thecarbide layer remains without being completely removed).

Note that the effects of deformation of the resin protrusion 20 on thesecond portion 32 can be reduced when the second portion 32 is notsecured to the resin protrusion 20. Therefore, the second portion 32 canbe prevented from breaking even if the width of the second portion 32 isreduced.

The first portion 31 of the interconnect 30 formed on the top surface ofthe resin protrusion 20 is the portion used for electrical connectionwith other electronic parts and the like. Therefore, it is preferablethat the width of the first portion 31 be large in order to increase themounting properties of the semiconductor device. The top surface of theresin protrusion 20 is almost parallel to the surface of thesemiconductor substrate. Therefore, the carbide layer on the top surfaceof the resin protrusion 20 can be reliably removed by a known method.Specifically, an electrical short circuit rarely occurs between thefirst portions 31 of two adjacent interconnects 30 even if the intervalbetween the first portions 31 is reduced.

Therefore, the semiconductor device according to this embodiment allowsprovision of a semiconductor device which exhibits excellent mountingproperties and high electrical reliability.

FIG. 3 shows an electronic module 1000 on which the semiconductor device1 is mounted. In the example shown in FIG. 3, the semiconductor device 1is mounted on a substrate 2. The substrate 2 may be a flexiblesubstrate, for example. The semiconductor device 1 may be mounted sothat the surface on which the interconnect 30 is formed faces thesubstrate 2. An interconnect of the substrate 2 and the interconnect 30of the semiconductor device 1 may contact each other and be electricallyconnected. In more detail, the interconnect of the substrate 2 and thefirst portion 31 of the interconnect 30 may contact each other and beelectrically connected. This allows the interconnect 30 (first portion31) to be pressed against the interconnect of the substrate 2 due to theelasticity of the resin protrusion 20. Therefore, an electronic moduleexhibiting high electrical connection reliability can be provided. Thesemiconductor device 1 may be bonded to the substrate 2 using anadhesive (resin-based adhesive). The electronic module 1000 may be adisplay device. The display device may be a liquid crystal displaydevice or an electroluminescent (EL) display device. The semiconductordevice 1 may be a driver IC which controls the display device.

Method of Manufacturing Semiconductor Device

FIGS. 4A to 7 are views illustrative of a method of manufacturing asemiconductor device according to one embodiment of the invention.

The method of manufacturing a semiconductor device according to thisembodiment includes providing the semiconductor substrate 10 includingthe electrode 14 shown in FIGS. 4A and 4B. The semiconductor substrate10 may be provided in the shape of a wafer, for example. As shown inFIG. 4A, the semiconductor substrate 10 in the shape of a wafer mayinclude a plurality of areas 11 in which the semiconductor devices arerespectively formed. As shown in FIG. 4B, the semiconductor substrate 10may include the passivation film 16. An opening 17 may be formed in thepassivation film 16. The semiconductor substrate 10 may include an oxidefilm 18. The oxide film 18 may be formed on the electrode 14. The oxidefilm 18 may be formed on the electrode 14 in the area in which the oxidefilm 18 overlaps the opening 17. As shown in FIG. 4B, the oxide film 18may be formed inside the opening 17.

The method of manufacturing a semiconductor device according to thisembodiment includes forming the resin protrusion 20 on the semiconductorsubstrate 10 (see FIG. 5C). The method of forming the resin protrusion20 is not particularly limited. An example of the method of forming theresin protrusion 20 is described below with reference to FIGS. 5A to 5C.As shown in FIG. 5A, a resin material 21 is provided on thesemiconductor substrate 10 (passivation film 16). As shown in FIG. 5B,the resin material 21 is patterned. The resin material 21 may be thencured (e.g. thermally cured) to form the resin protrusion 20, as shownin FIG. 5C. In the step of forming the resin protrusion 20, the resinmaterial 21 may be melted and then cured to form the resin protrusion 20having a curved surface.

The method of manufacturing a semiconductor device according to thisembodiment may include removing at least part of the oxide film 18 toexpose the electrode 14, as shown in FIG. 6. The surface of the topportion of the resin protrusion 20 may be carbonized by this step toform a carbide layer. This step may be performed using Ar gas. Forexample, this step may include disposing the semiconductor substrate 10in an Ar gas atmosphere (atmosphere containing Ar ions), andaccelerating the Ar ions utilizing the potential difference to cause theAr ions to collide with the oxide film 18. In this case, the oxide film18 may be scattered by causing the Ar ions to collide with the oxidefilm 18 to expose the electrode 14. This step may be performed using gasother than the Ar gas.

The method of manufacturing a semiconductor device according to thisembodiment includes forming the interconnect 30 electrically connectedwith the electrode 14, as shown in FIG. 7. The interconnect 30 is formedto extend over the top portion of the resin protrusion 20. Theinterconnect 30 is formed to include the first portion 31 formed on thetop surface of the resin protrusion 20 and the second portion 32 formedon the lower portion of the resin protrusion 20. The method of formingthe interconnect 30 is not particularly limited. For example, theinterconnect 30 may be formed by forming metal foil by sputtering andpatterning the metal foil. In the step of patterning the metal foil, theinterconnect 30 may be formed so that the second portion 32 has a widthsmaller than that of the first portion 31. In this step, the first andsecond portions 31 and 32 may be formed to contact the resin protrusion20, as shown in FIG. 7. In this case, the first and second portions 31and 32 may be secured to the resin protrusion 20.

The method of manufacturing a semiconductor device according to thisembodiment may include partially removing a carbide layer formed on thesurface of the resin protrusion 20 after the step of forming theinterconnect 30. In this case, a portion of the carbide layer exposedfrom the interconnect 30 may be removed. This step may be performedusing O₂ plasma, for example. The surface of the resin protrusion 20faces almost the same direction as the semiconductor substrate 10 nearthe top portion of the resin protrusion 20. Therefore, the carbide layerformed on the surface of the top portion of the resin protrusion 20 canbe efficiently and reliably removed by using O₂ plasma. In this step, atleast part of the portion of the lower portion of the resin protrusion20 which contacts the second portion 32 may be removed. This may createa state in which at least part of the second portion 32 is not securedto the resin protrusion 20 (see FIG. 1B). For example, the portion ofthe resin protrusion 20 which contacts the second portion 32 may beremoved by utilizing an etchant (e.g. etching gas or liquid etchant). Asdescribed above, the second portion 32 has a width smaller than that ofthe first portion 31. Therefore, the etchant can reach the back side ofthe second portion 32. Specifically, the back side of the second portion32 can be easily etched. Therefore, this method allows a highly reliablesemiconductor device to be efficiently manufactured.

A step of cutting the semiconductor substrate 10, an inspection step,and the like may be then performed to obtain the semiconductor device 1.

The invention is not limited to the above-described embodiments, andvarious modifications can be made. For example, the invention includesvarious other configurations substantially the same as theconfigurations described in the embodiments (in function, method andresult, or in objective and result, for example). The invention alsoincludes a configuration in which an unsubstantial portion in thedescribed embodiments is replaced. The invention also includes aconfiguration having the same effects as the configurations described inthe embodiments, or a configuration able to achieve the same objective.Further, the invention includes a configuration in which a publiclyknown technique is added to the configurations in the embodiments.

Although only some embodiments of the invention have been described indetail above, those skilled in the art will readily appreciate that manymodifications are possible in the embodiments without departing from thenovel teachings and advantages of this invention. Accordingly, all suchmodifications are intended to be included within the scope of thisinvention.

1. A flexible substrate comprising: an electrode; a resin protrusionformed on a surface of the flexible substrate; and an interconnectelectrically connected to the electrode and formed to extend over theresin protrusion, the interconnect including a first portion formed on atop surface of the resin protrusion and a plurality of second portionsformed on side surfaces of the resin protrusion that are lower than thetop surface of the resin protrusion, and each of the second portionshaving a width smaller than a width of the first portion, and the firstportion being located between the plurality of second portions.
 2. Theflexible substrate as defined in claim 1, wherein the interconnectincludes an extension portion extending from one of the second portions,and a conductive portion connecting the extension portion and theelectrode; and wherein the extension portion has a width smaller than awidth of the conductive portion.
 3. The flexible substrate as defined inclaim 2, wherein the extension portion has a width equal to the width ofthe one of second portions.
 4. The flexible substrate as defined inclaim 1, wherein a portion of the interconnect formed on the substratehas a width equal to the width of the second portions.
 5. The flexiblesubstrate as defined in claim 1, wherein the second portions of theinterconnect are not secured to the resin protrusion.
 6. A flexiblesubstrate comprising: an electrode on a surface of the flexiblesubstrate; a resin protrusion on the surface of the flexible substrateadjacent the electrode; and an interconnect electrically connected tothe electrode and crossing over the resin protrusion, the interconnectincluding: a first portion on a surface of the resin protrusion, thefirst portion being spaced apart from the substrate by a pair ofexpanses along the surface of the resin protrusion; and a pair of secondportions on the surface of the resin protrusion, the pair of secondportions extending in opposite directions from the first portion andtraversing the expanses along the surface of the resin protrusion to thesubstrate, each of the second portions being narrower than the firstportion.
 7. The flexible substrate as defined in claim 6, theinterconnect further comprising: an extension portion on the flexiblesubstrate and extending from one of the second portions, and aconductive portion connecting the extension portion and the electrode;the extension portion being narrower than the conductive portion.
 8. Theflexible substrate as defined in claim 7, the extension portion having awidth equal to a width of the one second portion.
 9. The flexiblesubstrate as defined in claim 6, the interconnect further comprising: anextension portion on the flexible substrate and extending from one ofthe second portions, the extension portion having a width equal to awidth of the one second portion.
 10. The flexible substrate as definedin claim 6, wherein the pair of second portions of the interconnect arenot secured to the resin protrusion.